1993 transmission acting up (throws out of gear, lost reverse, starting in higher gear)

Joined
Jan 21, 2009
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48
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Louisiana
Good afternoon everyone!
A month or so ago I picked up a 1993 Land Cruiser, automatic transmission, tripple locked. PO said after some water crossings he started experiencing transmission throwing out of gear, then at the full stop it feels like it's in a high gear, then sometimes it will kick back in first gear when you give it gas. Also lost reverse. Everything defaults back to normal when you kill the engine and start again.
He changed the solenoids in the transmission, swapped the ICU, fluids. He did say that one of the connector going from the engine to the transmission was corroded inside which he cleaned up and electrical taped. I can see a couple more connectors which he didn't get to.
Has any of you experienced anything similar? No codes.
Thanks

IMG_20220118_112749.jpg
 
Joined
Dec 12, 2010
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Denver
Good afternoon everyone!
A month or so ago I picked up a 1993 Land Cruiser, automatic transmission, tripple locked. PO said after some water crossings he started experiencing transmission throwing out of gear, then at the full stop it feels like it's in a high gear, then sometimes it will kick back in first gear when you give it gas. Also lost reverse. Everything defaults back to normal when you kill the engine and start again.
He changed the solenoids in the transmission, swapped the ICU, fluids. He did say that one of the connector going from the engine to the transmission was corroded inside which he cleaned up and electrical taped. I can see a couple more connectors which he didn't get to.
Has any of you experienced anything similar? No codes.
Thanks

View attachment 2902979
The super corroded connector is usually the Gear position sensor. The other connector there isn’t immune by any stretch. If they were both corroded to the point of intermittent contact, I would suspect very erratic behavior. The good news is that if you fix it, and still have to replace the trans, it will no longer be of worry.

The gear position sensor comes with one end of the connector, the other side is NLA as far as I know, so you’ll need to rob it from a donor harness. You could always replace the factory connector with another brand or different style Toyota connector.
 
Joined
Jan 21, 2009
Messages
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Louisiana
The super corroded connector is usually the Gear position sensor. The other connector there isn’t immune by any stretch. If they were both corroded to the point of intermittent contact, I would suspect very erratic behavior. The good news is that if you fix it, and still have to replace the trans, it will no longer be of worry.

The gear position sensor comes with one end of the connector, the other side is NLA as far as I know, so you’ll need to rob it from a donor harness. You could always replace the factory connector with another brand or different style Toyota connector.
Thanks! Everything is so tight there, can't really stick my hands in there... Thinking about dropping the transmission. Or lifting the body o_O
 
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Messages
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Thanks! Everything is so tight there, can't really stick my hands in there... Thinking about dropping the transmission. Or lifting the body o_O
If you pull the starter, you can get your hands up there and get them disconnected (a PITA by itself), you can pull the trans side down and repair fairly easily. The engine harness side is much easier to repair if you pull it up past the intake manifold and lay it out on the engine bay. If you raise the truck and pull the tire and rubber fender sill you can get to it to inspect it well and you can repair it from this position, but it’s frustrating.
 
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Jan 21, 2009
Messages
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Louisiana
If you pull the starter, you can get your hands up there and get them disconnected (a PITA by itself), you can pull the trans side down and repair fairly easily. The engine harness side is much easier to repair if you pull it up past the intake manifold and lay it out on the engine bay. If you raise the truck and pull the tire and rubber fender sill you can get to it to inspect it well and you can repair it from this position, but it’s frustrating.
Yes that's what I did today, pulled the tire off, the rubber thing (broke the clips lol). It was cold today but I feel I had good time learning what's where. Thanks for the advice!!
 
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I took it for a drive later, it worked ok, i just drove it around the block a couple of times, it shifted well. I feel like I'm starting to have issues when it gets warm.
 
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Jan 21, 2009
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You know this made me think. There is a transmission cooler, right? What if there's something wrong with that? I'm not getting any warning lights about transmission fluid overheating though..
 
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Common issue with the NSS (neutral Safety Switch) barrel connector. Can be worked, but as mentioned must remove drivers tire, inner fender flaps and by personal experience you will need a good head lamp and a strong will to want to do it. Unplug, find the corroded ones and wire those around connector. Seems like 7 wires in all but typically only 2 or 3 connections are bad. There’s lots of threads about the NSS connector and many I have replied to. Might do a search. As I recall someone even sorted out every wire and color in a diagram.
 
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Common issue with the NSS (neutral Safety Switch) barrel connector. Can be worked, but as mentioned must remove drivers tire, inner fender flaps and by personal experience you will need a good head lamp and a strong will to want to do it. Unplug, find the corroded ones and wire those around connector. Seems like 7 wires in all but typically only 2 or 3 connections are bad. There’s lots of threads about the NSS connector and many I have replied to. Might do a search. As I recall someone even sorted out every wire and color in a diagram.
Awesome, thank you, will do some more searching (NSS keyword helps, thanks!)
 
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I think @SUMMIT CRUISERS has given you a good place to start. Lots of posts on the NSS acting up. He is also right that it is a PIA to both get to the barrel connector and get it disconnected. I cleaned up my NSS and barrel connector when I replaced my starter contacts, since having the starter removed gives you more room to work. Didn't solve my transmission issues, but that's life.
 
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I think @SUMMIT CRUISERS has given you a good place to start. Lots of posts on the NSS acting up. He is also right that it is a PIA to both get to the barrel connector and get it disconnected. I cleaned up my NSS and barrel connector when I replaced my starter contacts, since having the starter removed gives you more room to work. Didn't solve my transmission issues, but that's life.
Thanks, bummer it didn't solve your transmission issues though :/
 

PNWTreeOctopus

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I had some issues with my NSS harness on my 1993. They are different from yours to a point. I had no gear holding in 2 or L, it would shift through like it was in D. My reverse lights did not function. My R gear indicator light in the dash did not function.

My NSS barrel connector had probably been bathed in weeping coolant from an old PHH. It was very difficult to separate. Several pins disintegrated when I cleaned them. I bought a new NSS and things were still not functioning correctly because the harness side connectors were too corroded to conduct and several wires had broken off below the connector.
IMG_5473.jpeg
In the end I bought a 9 pin (IIRC only 8 are needed) connector with pig tails and cut and spliced it with heat shrink crimp connectors. I wrapped it up in some high quality harness tape and It solved my slipping transmission problems. Its also worth noting that the NSS connectors for the trans on our rigs (93-94) are different from the 95+ rigs.

Getting into that space is really uncomfortable. I did not remove the starter. I found that the shock tower and the actual fender panel were the things most in my way. Once I freed the barrel connector the first time it was easier to deal with. The lower harness is NLA and the barrel connector was impossible to track down. It was far easier to source a quality 9 pin waterproof pigtail and go that direction. My baseline thread has my saga all laid bare, including wiring questions. A FSM and the supplemental 93 wiring diagram are very helpful.

In the end you will need to check the continuity between the pins as shown in the FSM and EWD. Its not particularly hard, but its tight and uncomfortable.

Feel free to PM me if you want more detail.
 
Joined
Jan 21, 2009
Messages
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I had some issues with my NSS harness on my 1993. They are different from yours to a point. I had no gear holding in 2 or L, it would shift through like it was in D. My reverse lights did not function. My R gear indicator light in the dash did not function.

My NSS barrel connector had probably been bathed in weeping coolant from an old PHH. It was very difficult to separate. Several pins disintegrated when I cleaned them. I bought a new NSS and things were still not functioning correctly because the harness side connectors were too corroded to conduct and several wires had broken off below the connector. View attachment 2907901In the end I bought a 9 pin (IIRC only 8 are needed) connector with pig tails and cut and spliced it with heat shrink crimp connectors. I wrapped it up in some high quality harness tape and It solved my slipping transmission problems. Its also worth noting that the NSS connectors for the trans on our rigs (93-94) are different from the 95+ rigs.

Getting into that space is really uncomfortable. I did not remove the starter. I found that the shock tower and the actual fender panel were the things most in my way. Once I freed the barrel connector the first time it was easier to deal with. The lower harness is NLA and the barrel connector was impossible to track down. It was far easier to source a quality 9 pin waterproof pigtail and go that direction. My baseline thread has my saga all laid bare, including wiring questions. A FSM and the supplemental 93 wiring diagram are very helpful.

In the end you will need to check the continuity between the pins as shown in the FSM and EWD. Its not particularly hard, but its tight and uncomfortable.

Feel free to PM me if you want more detail.
Thanks! Yeah, this is some tight space there. I have been waiting for a warmer weather (Louisiana stays hot and humid for the most part but it's been cold and humid, to make things worse). My next move is to remove, clean the NSS and see if that fixes my issues. Thanks again!
Did you get your issues solved?
 

PNWTreeOctopus

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Yes. My transmission now holds in 2 and L and the reverse lights came back. Separating the plugs was more challenging than I expecting. The cramped conditions makes it difficult to get much leverage. I bought some electrical contact cleaner and I think spraying it with that helped loosen things up. I also bought a soft jaw slip joint pliar like these K tool cannon plug pliers or the equivalent. These helped me a bunch, but in the end I found they were just a PITA and needed so much force. You might learn a lot just inspecting the plug and that region of your block. You may discover the wires have corroded behind the plug.

Given the PO’s water crossing history I’ll bet there is some corrosion there. If the connectors are all oxidized and non conductive you could try a micro file, or do some research on removing the oxidation. I sprayed white vinigar on mine, agitated with some qtips the sprayed it all clean with contact cleaner until the vinigar was gone. In the end my connectors were too far gone and cleaning them made some crumble. It was very intimidating to cut the plug and re wire, but it made my cruiser functional again. If I can do it, anybody can.

Definitely be careful not to break off the connectors to the knock sensors, since they are sort of nearby and all our plastic connectors are nearly 30 years old and brittle AF.
 
Joined
Jan 21, 2009
Messages
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Yes. My transmission now holds in 2 and L and the reverse lights came back. Separating the plugs was more challenging than I expecting. The cramped conditions makes it difficult to get much leverage. I bought some electrical contact cleaner and I think spraying it with that helped loosen things up. I also bought a soft jaw slip joint pliar like these K tool cannon plug pliers or the equivalent. These helped me a bunch, but in the end I found they were just a PITA and needed so much force. You might learn a lot just inspecting the plug and that region of your block. You may discover the wires have corroded behind the plug.

Given the PO’s water crossing history I’ll bet there is some corrosion there. If the connectors are all oxidized and non conductive you could try a micro file, or do some research on removing the oxidation. I sprayed white vinigar on mine, agitated with some qtips the sprayed it all clean with contact cleaner until the vinigar was gone. In the end my connectors were too far gone and cleaning them made some crumble. It was very intimidating to cut the plug and re wire, but it made my cruiser functional again. If I can do it, anybody can.

Definitely be careful not to break off the connectors to the knock sensors, since they are sort of nearby and all our plastic connectors are nearly 30 years old and brittle AF.
Great to hear you got it fixed! Thank you for the heaps of good info! I'll keep this thread updated.
 
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Update. Decided to check the NSS since it's the easiest to get to. The brass contacts did have some wear, some grooves. I sanded them with 220 grit, made sure they're straight, no grooves. Inside the switch everything seemed ok. Cleaned it, applied dielectric grease, closed it up and reinstalled. Now, I did notice that the bolts holding it were somewhat loose.
Did a drive test, had to adjust the position a little. At first it was acting erratic, reverse would be there then would disappear, same for the gears. Adjusted the NSS position a little, starts at P but not at N, can't check the reverse lights now. It started off great, like I had 1st and all the rest of the gears and the reverse. After about 10 minutes of driving when I pushed it a bit and accelerated it threw me out of gear again at about 45mph. Then it started acting up again. At stops it would start in third or something.
Kill the engine, everything seems ok again.
Next thing is to try to get to the plug again but I feel it starts acting up when it gets warm/hot.
On the separate subject, I noticed blue smoke coming out when I first started the engine (hasn't been started in a week or so) :/
 

PNWTreeOctopus

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When you say it threw you out of gear…did you mean it shifted unexpectedly? You were in D? You need to check the NSS connectors. They are hard to get to, but important to rule out.
 

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